The present invention relates to a timepiece device provided with a rechargeable power-generator mechanism and in particular to a mechanism for indicating that timepiece pointer movement has resumed following a halt condition.
Conventional timepiece devices that provide a power-generator mechanism for generating necessary electrical energy for timepiece driving are currently in use and under development. Power-generator mechanisms of this type include those that use solar cells to charge a rechargeable battery. Others, including wristwatches, recharge a rechargeable battery with the output of a built-in, automatically-activated power-generator mechanism which generates power in accordance with the natural movement of the user's hand. Normally, if the timepiece device is moved or shaken, the rechargeable battery is sufficiently charged and the timepiece-device pointers are driven at a velocity which represents the passage of time.
However, if the timepiece device is not moved, the rechargeable battery will no longer receive charge from the power-generating mechanism, and because the pointers are still being driven, the rechargeable battery will eventually be drained of charge. As a result, the normal movements of pointers will cease and the timepiece device enters into a halt condition. When the timepiece device is then moved or shaken, the power-generating mechanism starts recharging the battery, and the pointers' movement resumes.
A problem associated with timepiece-devices of this type is that the timepiece-device user may not realize that pointer movement has resumed from a halt. For example, in a timepiece device with two pointers, a minute and an hour pointer, pointer movement is too slow to be recognized by the user for the user to recognize by glancing at the timepiece device that pointer movement has halted or restarted. Therefore, the user may not realize that battery recharging and pointer movement has resumed following a halt condition.
To overcome this drawback, timepiece devices include "modulated movements of pointer" in which at least one pointer is driven at a faster than normal velocity. Modulated movements of pointers occurs when charging of the rechargeable battery has resumed after a halt condition. Modulating the pointers in such a manner informs the user that pointer movement has just resumed from a halt condition.
A drawback in using this technique is that the modulated movement of pointers consume more power than normal movements of pointers and may cause the rechargeable battery to drain faster than the battery can be recharged. Thus, if modulated movement of pointers is initiated immediately after the rechargeable battery has resumed charging following a halt condition, the battery charge will be quickly drained to a level that is below what is necessary for activating the timepiece device. This causes the modulated movement of pointers to terminate and the timepiece device to reenter into a halt condition. Therefore, by starting modulated movement of pointers immediately after the resumption of battery recharging following a halt condition, it is impossible to ensure secure and reliable timepiece pointer movements.
Another problem with prior art devices that use the modulated movement of pointers technique is that timepiece device batteries do not always charge uniformly and the charge contained in these batteries may fluctuate irregularly. Also, some batteries have a superficial charging voltage that is different from the real charging voltage and therefore does not reflect the real charging condition of the battery. In these situations, the timepiece device may initiate modulated movements of pointers after a halt condition even though the amount of charge in the battery cannot sustain modulated pointer movements.
Therefore, it is desired to provide a timepiece device in which modulated movements of pointers can be used to inform the user that the timepiece device has restarted from a halt condition while also maintaining reliable and secure pointer movements following a halt condition.